At present, many products are produced using production lines which are working continuously. Frequently products moving along the production line by means of conveyor belts need to be repositioned correctly with respect to machines, so that the product may be required to be rotated about an axis perpendicular to the plane in which the product moves through the production line.
Such orientation is often done by using pushers or contacting devices. The product which is moved in a given direction, is prevented to move along at one of its sides, i.e. the right side or the left side with respect to the moving direction. As the right and left side of the product do not move at the same speed, a rotation about an axis perpendicular to the direction of movement is obtained.
Such mechanisms require that the product be contacted at at least one of its sides, and usually do not provide predictable movements of the product, hence necessitate additional manipulations.
Alternatively the product is clamped by a clamping means and manipulated, i.e. oriented, by rotating the clamping means.
Both mechanisms necessitate interaction of a machine part with the sides of the product not in contact with the conveyor belt. Such contact may, however, lead to damage on the sides of the product not contacting the conveyor belt. In particular, in case the product is a stack of sheet material, such as stacks of paper, cardboard or plastic sheets, the contact with the sides of the stack may cause misalignment of the stack and/or damage at the border of the sheets.